With the development of mobile technology, mobile devices, such as smart phones or tablets, have become more and more important in people's daily life. A mobile device is usually powered by a built-in battery. Due to the nature of the mobile device, the capacity of the built-in battery is often compromised to, for example, achieve better mobility. Therefore, power consumption needs to be taken into consideration when designing a mobile device.
A mobile device is equipped with a display screen to display information or contents. Usually, a fair amount of power is consumed by the display screen. Sometimes, for example, the display screen may consume about 70%-80% of the total power of the mobile device. Therefore, a battery life of the mobile device is often affected by the display screen. In the conventional technology, when the mobile device needs to display a piece of information or certain contents, the entire display screen needs to be powered on. Sometimes, the information or content that needs to be displayed only occupies a small portion of the display screen, and thus the rest of the display screen is not utilized but still consumes power. As a result, a lot of power is wasted, and the battery life of the mobile device is reduced.
To reduce the power consumption by a display screen, a mobile device may provide an option to reduce the brightness of the entire display screen. However, reducing the brightness may also reduce the readability of the contents displayed on the display screen, and thus affects the user experience.